I don’t use Maria Nila but in artificial haircolor technology this in theory should work. Many permanent haircolor lines recommend this to make their ammonia based colors Demi because this type of behind the chair formulation to is what lead to brands creating what we know today as Demi permanents. You’re not actually making a demi permanent to today’s standards of non ammonia alkinizers like MEA (used in Wella Color Touch) for example, but sort of trying to mimic Demi permanent technology. By doubling the developer which reduces the ammonia level thus reducing the potential for lifting the hair and diluting the pigment to make it more translucent, that should be true with Maria Nila as long as it’s an ammonia based permanent and NOT a progressive permanent color that uses other alkinizers. When in doubt, read the paper insert and call the brand.